ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
353 
Maturation and Fertilisation in Amphioxus.* — Dr. J. Sobotta has 
been able to make an essentially complete series of observations on tbe 
fertilisation-process in tbe eggs of Amphioxus lanceolatus. He also gives 
a detailed account of tbe formation of tbe second polar body,* but is 
unable to contribute anything to tbe question of reducing divisions. 
Tbe fertilisation processes conform to tbe usual plan ; tbe centrosomes of 
tbe fertilised ovum are wholly of paternal origin ; the chromatin is in 
half paternal and in half maternal ; no bint of a centre- quadrille or the 
like was to be seen. Tbe author finds bis results very different from 
those reached by 0. Van der Stricht, and believes that this careful Belgian 
investigator worked unconsciously with markedly polyspermic ova. 
Germinal Vesicle and Polar Bodies in Batrachia.j — MM. J. B. 
Carnoy and H. Lebrun began a study of these structures in 1887, and 
they speak of their patient work as ten years of bard labour. They start 
with a general essay on tbe structure of tbe cell, especially of tbe 
nucleus, comparing their own observations and conclusions with those of 
others. There are two other general chapters in tbe memoir, one entitled 
“ tbe karyoplasm and tbe cytoplasm,” and one dealing with nucleoli. 
Tbe first type discussed is Salamandra maculosa , in tbe eggs of which 
they find four types, characterised by tbe different resolutions of tbe 
nuclear filament. In order of frequency these types are : — (1) Besolution 
serpentine , (2) Besolution en houdins, (3) Besolution filamenteuse etoilee , 
and (4) Besolution en plumeaux. Tbe second type discussed is Pleuro- 
deles Waltii Mich. Here there are three types, characterised by tbe 
nucleolar figures of tbe first period. 
Ovary and Ovarian Ova in Marine Fishes.! — Mr. J. T. Cunning- 
ham deals especially with tbe development of tbe yolk. In fishes with 
pelagic ova and an annual spawning period, tbe formation of yolk com- 
mences some months after tbe close of tbe preceding spawning season. 
Tbe active development of tbe annual crop of ova does not take much 
more than six months. Tbe formation of yolk always begins near tbe 
surface of tbe cytoplasm, and extends inwards. If there are separate oil- 
globules, a few small ones are present before tbe yolk begins to be 
formed, except in tbe mackerel. In immature sole, turbot, brill, &c., 
examined during tbe spawning season, tbe largest ova in tbe ovaries con- 
tain scattered oil-globules. Tbe same is true in tbe largest transparent 
ova in spent ovaries of these species. When tbe formation of yolk takes 
place in such eggs, tbe oil-globules form a zone internal to tbe yolk. 
Tbe essential peculiarity of tbe spent ovary is tbe presence of rup- 
tured follicles ; tbe follicular epithelium seems to disintegrate and 
dissolve; tbe cavity is obliterated by tbe contraction of the follicle,, 
which forms a mass of cells and fibres, and is finally absorbed soon after 
yolk begins to be formed in tbe eggs of tbe following season. Some eggs 
which have never matured die. and are absorbed in situ. In tbe fresh 
state they are seen as opaque amorphous masses. Tbe same is true in 
unripe ovaries where spawning has never occurred. 
The vitelline nucleus is first seen as a stained corpuscle in contact 
* Arch. f. Mikr. Anat., 1. (1897) pp. 15-71 (4 pis.). 
t La Cellule, xii. (1897) pp. 191-295 (5 pis.). 
X Quart. Journ. Micr. Sci., xl. (1897) pp. 101-63 (3 pis.). 
2 c 2 
